1. Technical Field of the Invention
The present invention relates to a metal plate coated stainless material, and a method of producing a metal plate coated stainless material.
2. Description of the Related Art
Conventionally, as an electrical contact material used in connectors, switches, printed wiring boards and the like, a metal plate coated stainless material in which the surface of a stainless steel sheet is coated with a metal plated layer formed from any one metal among Ag, Pd, Pt, Rh, Ru, Cu, Sn and Cr, or an alloy composed of at least two or more of these metals, has been used.
Usually, in such a metal plate coated stainless material formed with a metal plated layer at the surface, an underlying nickel plating is performed to form an underlying nickel plated layer on the stainless steel sheet before forming the metal plated layer, in order to improve the interfacial adhesion property of the metal plated layer at the surface. In this case, when the metal plated layer is formed on such an underlying nickel plated layer, if defects such as pinholes occur in the metal plated layer, nickel will dissolve from the underlying nickel plated layer thereby to cause delamination of the metal plated layer, which may be problematic.
To overcome this problem, for example, Patent Document 1 discloses a technique of forming a gold plated layer directly on a stainless steel sheet without performing such underlying nickel plating.